Fix: replace xxx placeholder in migration script comment

Replaced the `xxx` placeholder in `scripts/migrate_syntax.py` with `<module>` to prevent automated issue trackers from falsely flagging the documentation line as an unresolved TODO. Adjusted the trailing formatting to maintain line length.

Co-authored-by: Tcode-Motion <188012755+Tcode-Motion@users.noreply.github.com>

Author: google-labs-jules[bot]

scripts/migrate_syntax.py

@@ -34,7 +34,7 @@
     (r'std\.io\.println\((.+?)\)', r'say \1', 0),
     (r'std\.io\.print\((.+?)\)', r'say \1', 0),
 
-    # ── std.xxx.yyy() calls → module.yyy() ─────────────────────────────────
+    # ── std.<module>.yyy() calls → module.yyy() ────────────────────────────
     (r'std\.math\.', r'math.', 0),
     (r'std\.strings\.', r'string.', 0),
     (r'std\.fs\.', r'file.', 0),